Wednesday, September 27, 2017

A Very Hungry Caterpillar Is Killing Trees in New England

Climate change is partly to blame.  So is an amateur entomologist who lived in the 1800s.

Gypsy moth caterpillars have been munching on New England’s trees, causing widespread damage. (Photo credit: USFWS/James Appleby) Click to Enlarge.
During the summer, gypsy moth caterpillars have been munching on the forest’s green canopy, leaving trees across Connecticut and Rhode Island leafless.  According to Heather Faubert, who runs the Plant Protection Clinic at the University of Rhode Island, the caterpillars prefer oak and apple leaves when they’re young.  But as they grow and the population expands, they’ll feed on just about any kind of tree.
The main threat to the gypsy moth in North America is a Japanese fungus called Entomophaga maimaiga.  But the fungus dies during prolonged drought, and the northeast has experienced unusually dry, early springs and dry, hot summers during the past three years.
The caterpillars pose a threat to forests.  In large numbers they can completely defoliate trees and even forest understories.  In 2016, over 350,000 acres of Massachusetts forests were defoliated by gypsy moths.  This defoliation stresses the trees and can kill them.
But wait, what caused the drought?
The relationship between climate change and precipitation is complicated.  As the climate warms, overall precipitation has increased.  But rainfall is concentrated in quick, extreme events instead of spread out over time.  Winters in the northeast have also seen a decrease in snow coverage, which can contribute to a drier spring season, since there is less snow melt.

According to Jeanne Brown, communications and outreach manager at the Northeast Climate Science Center, summers in the northeast are expected to get much warmer. Without action to reduce greenhouse gas emissions, average summer temperatures in Massachusetts are projected to increase by 8 degrees F. And warmer temperatures, Brown said, mean higher potential for dry spells.

All of these factors, according to research by the University of Massachusetts at Amherst, contribute to drought in New England. “Warming and less frequent precipitation events favor an increase in drought intensity,” the report said. That could make for fundamental changes in the landscapes of New England.

Read more at A Very Hungry Caterpillar Is Killing Trees in New England

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